The present invention relates to a new and improved method of regulating the current of a circulating-currentfree or loop-currentfree rectifier circuit arrangement, especially in an anti-parallel circuit arrangement, wherein the operating point, needed after switching from one rectifier arrangement to the other rectifier arrangement, for igniting the latter is continuously followed-up or readjusted, and this invention also pertains to a new and improved apparatus for the performance of the aforesaid method aspects.
There are already known to the art current rectifier drives for a circulating-currentfree anti-parallel circuit arrangement and, for instance, the regulation behavior thereof has been described in considerable detail in the following German language publication:
Technische Mitteilungen AEG-Telefunken 60 (1970) 6, Entitled: "Die Regeldynamik von Stromrichterantrieben in kreisstromfreier Gegenparallelschaltung", authored by Arne Buxbaum.
This publication in its summary states that the simplest circulating-currentfree anti-parallel circuit, the circuit utilizing switching of the pulses, possesses relatively poor regulation dynamics. It is only possible to obtain a limited improvement by means of a regulation control. This circuit and its shortcomings have been listed in the aforementioned publication under point 3. As therein stated a switching-current rectifier is equipped with a regulation control having two pulse control devices, two current regulators and an additional regulation control or adjustment means. The regulation adjustment means insures that the current regulator of the current rectifier arrangement which is not in an active state will be readjusted as a function of the electromotive force (EMF) of the motor in such a way that after switching to such current rectifier arrangement the output voltage of the regulator corresponds to the required control of the current rectifier. With this arrangement the prolonged currentless intervals or pauses and the prolonged regulation times following the switching operation can be avoided. There only remains the null-time brought about by the required waiting time of the switching stage. Owing to the necessary limitations this circuit arrangement has not proven to be satisfactory in practice.
Moreover, from the subsequent explanations of the shortcomings described in this publication it can be recognized that the regulation control only operates faultlessly in the non-interrupted or gapless current range. With increased expenditure it is only partially possible to obtain satisfactory functioning in the interrupted or gap current range.